Fuel Tank Pressure Sensor
WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The fuel tank pressure (FTP) sensor measures the difference between the pressure or vacuum in the fuel tank and outside air pressure. The control module provides a 5-volt reference and a ground to the FTP sensor. The FTP sensor provides a signal voltage back to the control module that can vary between 0.1-4.9 volts. As FTP increases, FTP sensor voltage decreases, high pressure equal low voltage. As FTP decreases, FTP voltage increases, low pressure or vacuum equal high voltage.